The present invention relates to a chuck having T-slots, adapted to receive slot blocks for the fastening of stops or rests, on the body of the chuck or on base jaws guided for radial movement within the body of the chuck by at least one attachment screw which engages into a slot block.
In the known constructions, the blocks which are displaceable in the T-slots of either the chuck body or the clamping jaws, may be thrown out of the slots together with the stops or rests arranged on them, when the chuck is rotating if the attachment screws which engage into the slot blocks are not properly tightened, since the securing of the blocks in position in the T-slots is effected exclusively by force-locking by means of the attachment screws and there are no form-interlocking stops which prevent the emergence of the blocks out of the slots in radially outward direction. Thus in the known constructions it is left solely to the care exercised by the operator to prevent accidents of parts being thrown out of the chuck.
The object of the present invention is to guarantee, by simple structural means, in a chuck of the afore-mentioned type, that even if the attachment screws are not properly tightened the blocks cannot be thrown out of the T-slots of the chuck body or the clamping jaws.